The overall objectives of the proposed research are to couple metabolically active primary cultures of liver cells or metabolically liver enzyme preparations with malignantly transformable C3H/10T1/2 mouse embryo cells to induce in vitro transformation of the mouse cells with known, potent and weak, liver carcinogens. The accomplishments of the current year are as follows: Techniques for maintaining metabolically active (as determined by measuring peroxidase activity and glucose-6-phosphatase activity) and morphologically intact (by scanning electron microscopy and transmission electron microscopy) primary liver cell mediated and rat liver enzyme mediated cytotoxicity of C3H/10T1/2 cells with the liver carcinogens has been achieved.